As described in German patent 3,437,803 of E. Butz a motor-vehicle headrest is typically carried at the upper end of an upright rod that is vertically slidable in a sleeve mounted on a seat back or behind a seat back on a shelf. The rod is vertically displaceable in the sleeve so that the vertical position of the headrest cushion can be adjusted. To this end the rod is typically formed with a row of horizontally open and vertically spaced notches and a horizontally biased latch element provided in the sleeve can engage in these notches to arrest the headrest in respective vertically offset positions.
Normally the latch element is a metallic part that is pressed by a spring toward the metallic rod. Such a system is fairly strong but has two main disadvantages. First of all, it can rattle, something that is particularly annoying in a motor vehicle, in particular when the source of the rattle is located at head level. Furthermore as the headrest is adjusted, the mutually engaging parts are subjected to considerable wear so that with time the headrest becomes loose, making any rattle even worse, or the system fails altogether.